In this work, the oceanographic aspects of the Golden Horn and some results of the Golden Horn Rehabilitation Project are presented. The hydrographic structure of the Golden Horn responds rapidly to the conditions in the southern Bosphorus, which is especially true for the outer parts of the estuary up to the Valide Sultan Bridge (VS). West of this bridge which was blocked by the pontoons of the bridge, carries the major pollution load and is dependent on the underlying water and surface mixing, for its renewal. The dissolved oxygen concentrations were measured below the detection limit in the region between the VS and Eyup-Sutluce (ES) section during the majority of the measurement periods where H2S has been determined simultaneously until February 2000. Although the microbial contamination of the estuary stations is very high, decreases in the contamination at stations are observed. The highest concentrations are recorded at the ES-VS section and supported by Fecal Coliform data during the rainy months in general despite the operational collector system surrounding the estuary. An obvious decrease of pollution in comparison with the data of the previous years is clearly observed as an encouraging result of the rehabilitation efforts achieved so far.